Frost dates for Ketchikan 10n, AK
At Ketchikan 10n, the median last spring frost (32°F) is Apr 20 and the median first fall frost is Oct 26, for a typical growing season of 189 days. For a 90% chance that the last frost has passed, wait until May 4. Nearby ZIP codes are in USDA hardiness zone 7b.
- Apr 20Last spring frost (median)50% chance of 32°F after this date
- May 4Safer planting date10% chance of 32°F after this date
- Oct 26First fall frost (median)50% chance of 32°F by this date
- 189 daysGrowing season (median)between 32°F freezes
Last spring frost dates
The chance that the temperature drops to the threshold after each date.
| Temperature | 90% chance later | 50% chance later | 10% chance later |
|---|---|---|---|
| 36°F | Apr 24 | May 6 | May 21 |
| 32°F | Apr 1 | Apr 20 | May 4 |
| 28°F | Mar 12 | Mar 29 | Apr 15 |
| 24°F | Jan 26 | Mar 2 | Mar 22 |
First fall frost dates
The chance that the temperature has dropped to the threshold by each date.
| Temperature | 10% chance by | 50% chance by | 90% chance by |
|---|---|---|---|
| 36°F | Sep 28 | Oct 9 | Oct 26 |
| 32°F | Oct 10 | Oct 26 | Nov 13 |
| 28°F | Oct 23 | Nov 14 | Dec 7 |
| 24°F | Nov 8 | Dec 5 | Jan 17 |
Growing season length
Days between the last spring and first fall freeze, as the length reached in 9, 5 and 1 out of 10 years.
| Temperature | 9 in 10 years at least | 5 in 10 years at least | 1 in 10 years at least |
|---|---|---|---|
| 36°F | 134 days | 156 days | 177 days |
| 32°F | 166 days | 189 days | 212 days |
| 28°F | 202 days | 227 days | 257 days |
| 24°F | 239 days | 277 days | 317 days |
Chance of a freeze in any year
| Temperature | Chance per year |
|---|---|
| 36°F | 100% |
| 32°F | 100% |
| 28°F | 100% |
| 24°F | 99% |
ZIP codes whose closest station is this one
| ZIP | Hardiness zone | Avg. extreme low | Distance |
|---|---|---|---|
| 99901 | 7b | 5 to 10°F | 37 km |
Not the official USDA Plant Hardiness Zone Map. Zones shown here are the values published in the USDA-ARS / Oregon State University PRISM Group 2023 ZIP code tables, shown unaltered. For the official interactive map, visit planthardiness.ars.usda.gov.
About this station
- NOAA station ID USC00504594, at 55.4519, -131.8183, elevation 90 m (295 ft).
- Data quality: Estimated from nearby stations (2+ years), 10 years of freeze data.
- Average days per year at or below 32°F: 76.
- Frost risk changes over short distances. Valleys and low spots freeze earlier than hillsides and city centers.
Nearby weather stations
- Ketchikan Intl Airport (13 km)
- Beaver Falls (13 km)
- Metlakatla 6 S (47 km)
- Annette Island Airport (48 km)
- Thorne Bay (52 km)
- Klawock Airport (80 km)
- Craig (83 km)
- Wrangell Airport (119 km)
Sources
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020, annual/seasonal normals by station (version 1.0.1), file dated June 27, 2023; documentation.
- USDA Agricultural Research Service and PRISM Group, Oregon State University, 2023 Plant Hardiness Zone Map ZIP code tables (CONUS, Alaska, Hawaii, Puerto Rico), files dated November 17, 2023. Data © PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed November 1, 2026. Official map: planthardiness.ars.usda.gov.
- U.S. Census Bureau, 2024 Gazetteer ZIP Code Tabulation Areas file, dated August 30, 2024 (ZIP centroids used to find the nearest station).
Freeze dates are 30-year probabilities, not forecasts. Check your local forecast before planting tender plants.